This invention relates generally to optical communication systems.
Conventionally, optical communications use a number of different wavelengths of light multiplexed over a common transmission path. The transmission path may be an optical fiber or waveguide. The waveguide may be part of a planar light circuit. A planar light circuit is an integrated circuit that includes an optical transmission path.
Conventionally, additional light signals of distinct wavelengths are added to the optical transmission path and light signals are removed from the optical transmission signal path by an optical add drop multiplexer (OADM). These multiplexers usually use Mach-Zehnder interferometers where identical Bragg gratings are created in two arms to add or drop a single wavelength channel. The Mach-Zehnder interferometers present challenges in planar grating fabrication, device dimensioning, and wafer level production.
Thus there is a need for other ways to integrate optical components on planar light circuits.